1. Technical Field
The present disclosure relates generally to cluster ablation electrode systems and, more particularly, to systems, devices and methods for positioning and placing multiple electrodes in a target surgical site.
2. Background of Related Art
The use of radiofrequency electrodes for ablation of tissue in a patient's body is known. In a typical situation, a radiofrequency electrode comprising an elongated, cylindrical shaft with a portion of its external surface insulated is inserted into the patient's body. The electrode typically has an exposed conductive tip, which is used to contact body tissue in the region where the heat lesion or ablation is desired. The electrode is connected to a radiofrequency power source, which provides radiofrequency voltage to the electrode, which transmits the radiofrequency current into the tissue near its exposed conductive tip. This current usually returns to the power source through a reference electrode, which may comprise a large area conductive contact connected to an external portion of the patient's body.
In some applications, for example, tumor ablation procedures, multiple electrodes are inserted into the body in an array to enlarge ablation volumes.
In a particular application, arrays of high frequency electrodes are inserted into tumors. The electrodes are typically placed in a dispersed fashion throughout the tumor volume to cover the tumor volume with uniform heat, typically below about 45° C. The electrodes may be sequentially applied with high frequency voltage so that each electrode heats in sequence its neighboring tissue and then shuts off. Then, the next electrode does the same in a time series. This sequence of cycling the voltage through the electrodes continues at a prescribed frequency and for a period of time.
The electrode systems discussed above are limited by the practical size of lesion volumes they produce. Accordingly, electrodes with cooled conductive tips have been proposed. With cooling, radiofrequency electrode tips generally produce larger lesion volumes compared with radiofrequency electrodes, which are not cooled. For example, standard single cylindrical electrodes, with cooled tips, as described above, may make lesion volumes up to 3 to 4 cm in diameter in living tissue (e.g., the liver) by using cannulae of 1 to 2 mm in diameter and having exposed tip lengths of several centimeters.
Desirably, a configuration of radiofrequency electrodes, which can accomplish ablation in the range of 4 to 6 cm diameter or greater for the purpose of adequately treating large cancerous tumors in the body are necessary to effectively destroy the tumor and combat cancerous cells from spreading. It is further necessary that such an electrode system involve a simple geometry, reduced numbers of tissue insertions, facilitate planning of needle placement, and facilitate planning of heat ablation geometry and distribution.
An electrode system, which can be easily inserted into an organ or through the skin with minimal risk of hemorrhage and discomfort to the patient, is desirable.
According to yet another aspect of the present disclosure, an introducer is provided for facilitating the insertion of a cluster of electrodes into the body of a patient for tissue for performing tissue ablation. The introducer includes a body portion including a plurality of holes formed therein for selectively receiving a respective elongate shaft of the electrodes therethrough, wherein the holes of the introducer orient and space each electrode relative to one another, wherein the introducer includes a centrally disposed hole formed therein for receiving a guide needle therethrough.
The introducer may further include a distal introducer including a plurality of arrays of hole clusters formed therein each arranged in a linear row, wherein the rows of hole clusters are equally spaced from one another; and a proximal introducer including a plurality of arrays of holes formed therein each arranged in a linear row, wherein the rows of holes are equally spaced from one another.
The holes of each radial row of holes of the proximal introducer may be equally spaced from one another. In an embodiment, the proximal introducer includes six arrays of holes formed, wherein the rows of holes of the proximal introducer alternate between rows of six holes and rows of seven holes.
Each cluster of holes of the distal introducer may include a radially inner-most hole and a pair of radially outer-most holes. The radially outer-most holes may be offset an angle from an axis extending through the inner-most holes of each respective array of hole clusters. The inner-most holes of each radial row of clusters of the distal introducer may be equally spaced from one another.
The distal introducer may include six arrays of clusters formed therein arranged in a linear row. The rows of clusters of the distal introducer may alternate between rows of six clusters and rows of seven clusters.
Systems or devices which facilitate the positioning and placement of the radiofrequency electrodes relative to one another and relative to the target tissue volume are also desirable.